This Small Business Innovation Research (SBIR) Phase I project concerns the development of a novel biosensor utilizing an entirely new detection element assembly that is based on insect chemosensory proteins (CSPs). A sensitive, robust system to identify environmental carcinogens such as polycyclic aromatic hydrocarbons (PAHs) would greatly aid efforts to protect and improve public health. This proposal describes the development of such a device utilizing insect CSPs that have evolved very high analyte specificities over millions of years. Compared to existing technologies such as solid state detectors, antibody-based detectors, and so on, insect CSPs have several characteristics that make them more attractive as biosensor detector elements, including their resistance to sensor fouling while also remaining unaffected by the potential antigenicity of an analyte. This is particularly important in the case of PAHs since they are generally small molecules of low antigenicity. This Small Business Innovation Research (SBIR) Phase I project has the potential to effect several broader impacts. Firstly, the project will allow the development of a highly sensitive PAH detector that will enhance efforts to monitor these carcinogenic compounds in industrial, urban, and other environments. Moreover, the project will generate the foundation for a new class of sensor devices that utilize detector elements based on insect CSPs; these devices are intended to overcome current limitations in detector technology by providing highly robust, portable, inexpensive detector elements that are not limited by the size or antigenicity of their intended analytes and do not require specialized training or equipment to use. Since there are thousands of insect chemosensory proteins available from an incredible variety of insect species, sensor detector elements could be designed in order to recognize an equally wide variety of analytes. Thus, this project is the foundation for a novel detector platform technology.